A booster circuit is known that generates a high voltage by utilizing charging/discharging a capacitor and the coupling effect. In order to reduce an area of the circuit, for example, a capacitor of a booster circuit is formed by using an insulating film between a floating gate of a nonvolatile memory cell and a diffusion layer of a nonvolatile memory cell, and an insulating film between a control gate of a nonvolatile memory cell and a floating gate of a nonvolatile memory cell (for example, Japanese Laid-open Patent Publication No. H6-283667).
In a booster circuit, when electric charges accumulated in a capacitor are discharged to a grounding wire etc., some of the electric charges do not contribute to generate a high voltage. Hence, an efficiency to generate a high voltage by the booster circuit decreases and thereby power consumption increases.